Light chain amyloidosis (AL) is a hematological disorder that occurs when a clonal population of B cells overproduces immunoglobulin light chains. Once secreted, these light chain proteins misfold and form amyloid fibrils, which lead to organ malfunction and ultimately death. AL is particularly toxic to the kidneys, with ~85% of monoclonal light chains causing nephrotoxicity (Picken, Contrib Nephrol, 2007, 153, p. 135). AL is characterized by high mutational variability between patients, making it a good model system to understand the determinants of extracellular amyloid formation. We will begin by systematically addressing the role of key physiological factors, such as protein concentration, pH, urea, sodium chloride, temperature, and polyethylene glycol (a molecular crowding agent) in amyloid formation. We will also assess the role of different lengths and sulfation patterns of glycosaminoglycans (GAGs) on the rate of fibril formation. These studies will begin with in vitro fibril formation assays. Once we have identified physiological factors that modulate the rate of fibril formation, we will study the effects of these factors on amyloid formation using a patient derived AL plasma cell line. Finally, we will identify the amyloid fibril core of two fibril forming proteins by partially digesting the fibrils without disrupting the characteristic amyloid structure, then analyzing the soluble and insoluble components by mass spectrometry. PUBLIC HEALTH RELEVANCE The goal of the laboratory is to understand the molecular mechanisms of light chain amyloidosis. This knowledge will lead to the development of therapeutic strategies to treat the disease. We hope that insights gained from the study of light chain amyloidosis will have application in other amyloid-forming disorders.